ci: Merge requests from external repos
- The altbuilder jobs will get stuck because that runner is intentionally disabled for external repos
- Don't know yet how to live with that. Is there a way to "not-to-use" tag for external MRs?
- the package:docker job will fail because of
$CI_REGISTRY_IMAGE
- resolve by tagging the image with some constant string and use that var only when pushing to registry